Karl Ludwig von Bertalanffy (September 19, 1901 – June 12, 1972) was an Austrianbiologist known as one of the founders of general systems theory (GST). This is an interdisciplinary practice that describes systems with interacting components, applicable to biology, cybernetics, and other fields. Bertalanffy proposed that the classical laws of thermodynamics applied to closed systems, but not necessarily to "open systems," such as living things. His mathematical model of an organism's growth over time, published in 1934, is still in use today.[1]

Bertalanffy grew up in Austria and subsequently worked in Vienna, London, Canada, and the USA.

Ludwig von Bertalanffy was born and grew up in the little village of Atzgersdorf (now Liesing) near Vienna. The Bertalanffy family had roots in the 16th century nobility of Hungary which included several scholars and court officials.[2] His grandfather Charles Joseph von Bertalanffy (1833–1912) had settled in Austria and was a state theatre director in Klagenfurt, Graz, and Vienna, which were important positions in imperial Austria. Ludwig's father Gustav von Bertalanffy (1861–1919) was a prominent railwayadministrator. On his mother's side Ludwig's grandfather Joseph Vogel was an imperial counsellor and a wealthy Vienna publisher. Ludwig's mother Charlotte Vogel was seventeen when she married the thirty-four-year-old Gustav. They divorced when Ludwig was ten, and both remarried outside the Catholic Church in civil ceremonies.[3]

Ludwig von Bertalanffy grew up as an only child educated at home by private tutors until he was ten. When he arrived at his Gymnasium (a form of grammar school) he was already well trained in the habit of learning by reading, and he continued to study on his own. His neighbour, the famous biologist Paul Kammerer, became a mentor and an example to the young Ludwig.[4] In 1918 he started his studies at the university level in philosophy and art history, first at the University of Innsbruck and then at the University of Vienna. Ultimately, Bertalanffy had to make a choice between studying philosophy of science and biology, and chose the latter because, according to him, one could always become a philosopher later, but not a biologist. In 1926 he finished his PhD thesis (translated title: "Fechner and the problem of integration of the higher order") on the psychologist and philosopher Gustav Theodor Fechner.[4]

Bertalanffy met his future wife, Maria, in April 1924 in the Austrian Alps, and were almost never apart for the next forty-eight years.[5] She wanted to finish studying but never did, instead devoting her life to Bertalanffy's career. Later in Canada she would work both for him and with him in his career, and after his death she compiled two of Bertalanffy's last works. They had one child, a son who would follow in his father's footsteps by making his profession in the field of cancer research.

Today, Bertalanffy is considered to be a founder and one of the principal authors of the interdisciplinary school of thought known as general systems theory. According to Weckowicz (1989), he "occupies an important position in the intellectual history of the twentieth century. His contributions went beyond biology, and extended into cybernetics, education, history, philosophy, psychiatry, psychology and sociology. Some of his admirers even believe that this theory will one day provide a conceptual framework for all these disciplines".[2] Spending most of his life in semi-obscurity, Ludwig von Bertalanffy may well be the least known intellectual titan of the twentieth century.[6]

when rB{\displaystyle r_{B}} is the Bertalanffy growth rate and L∞{\displaystyle L_{\infty }} the ultimate length of the individual. This model was proposed earlier by August Friedrich Robert Pūtter (1879-1929), writing in 1920.[7]

The Dynamic Energy Budget theory provides a mechanistic explanation of this model in the case of isomorphs that experience a constant food availability. The inverse of the Bertalanffy growth rate appears to depend linearly on the ultimate length, when different food levels are compared. The intercept relates to the maintenance costs, the slope to the rate at which reserve is mobilized for use by metabolism. The ultimate length equals the maximum length at high food availabilities.[1]

Passive electrical schematic of the Bertalanffy module together with equivalent expression in the Energy Systems Language

The biologist is widely recognized for his contributions to science as a systems theorist; specifically, for the development of a theory known as general system theory (GST). The theory attempted to provide alternatives to conventional models of organization. GST defined new foundations and developments as a generalized theory of systems with applications to numerous areas of study, emphasizing holism over reductionism, organism over mechanism.

Foundational to GST are the inter-relationships between elements which all together form the whole.

Bertalanffy's contribution to systems theory is best known for his theory of open systems. The system theorist argued that traditional closed system models based on classical science and the second law of thermodynamics were inadequate for explaining large classes of phenomena. Bertalanffy maintained that “the conventional formulation of physics are, in principle, inapplicable to the living organism being open system having steady state. We may well suspect that many characteristics of living systems which are paradoxical in view of the laws of physics are a consequence of this fact.” [10] However, while closed physical systems were questioned, questions equally remained over whether or not open physical systems could justifiably lead to a definitive science for the application of an open systems view to a general theory of systems.

In Bertalanffy’s model, the theorist defined general principles of open systems and the limitations of conventional models. He ascribed applications to biology, information theory and cybernetics. Concerning biology, examples from the open systems view suggested they “may suffice to indicate briefly the large fields of application” that could be the “outlines of a wider generalization;” [11] from which, a hypothesis for cybernetics. Although potential applications exist in other areas, the theorist developed only the implications for biology and cybernetics. Bertalanffy also noted unsolved problems, which included continued questions over thermodynamics, thus the unsubstantiated claim that there are physical laws to support generalizations (particularly for information theory), and the need for further research into the problems and potential with the applications of the open system view from physics.

In the social sciences, Bertalanffy did believe that general systems concepts were applicable, e.g. theories that had been introduced into the field of sociology from a modern systems approach that included “the concept of general system, of feedback, information, communication, etc.” [12] The theorist critiqued classical “atomistic” conceptions of social systems and ideation “such as ‘social physics’ as was often attempted in a reductionist spirit.” [13] Bertalanffy also recognized difficulties with the application of a new general theory to social science due to the complexity of the intersections between natural sciences and human social systems. However, the theory still encouraged for new developments from sociology, to anthropology, economics, political science, and psychology among other areas.[citation needed] Today, Bertalanffy's GST remains a bridge for interdisciplinary study of systems in the social sciences.